Bathtub bottom wall step



FIG. 1 is a perspective view of a bathtub bottom wall step defined therein, where an occupant can sit and rest his feet;

FIG. 2 is a right side elevation view thereof, the left side being a mirror image thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a bottom plan view thereof.

The parts shown in dotted lines form no part of the invention. 

The ornamental design for a bathtub bottom wall step defined therein, as shown and described. 